Instant Notes: Analytical Chemistry

Section A – The nature and scope of analytical chemistry

A2 ANALYTICAL PROBLEMS

AND PROCEDURES

The most important aspect of an analysis is to ensure that it will provide useful

and reliable data on the qualitative and/or quantitative composition of a material

or structural information about the individual compounds present. The analyt-

ical chemist must often communicate with other scientists and nonscientists to

establish the amount and quality of the information required, the time-scale for

the work to be completed and any budgetary constraints. The most appropriate

analytical technique and method can then be selected from those available or new

ones devised and validated by the analysis of substances of known composition

and/or structure. It is essential for the analytical chemist to have an appreciation

of the objectives of the analysis and an understanding of the capabilities of the

various analytical techniques at his/her disposal without which the most appro-

priate and cost-effective method cannot be selected or developed.

The stages or steps in an overall analytical procedure can be summarized as

follows.

● Definition of the problem. Analytical information and level of accuracy

required. Costs, timing, availability of laboratory instruments and facilities.

● Choice of technique and method. Selection of the best technique for the

required analysis, such as chromatography, infrared spectrometry, titrimetry,

thermogravimetry. Selection of the method (i.e. the detailed stepwise instruc-

tions using the selected technique).

● Sampling. Selection of a small sample of the material to be analyzed. Where

this is heterogeneous, special procedures need to be used to ensure that a

genuinely representative sample is obtained (Topic A4).

Analytical
procedures

Analytical
problems

Key Notes

Selecting or developing and validating appropriate methods of analysis

to provide reliable data in a variety of contexts are the principal problems

faced by analytical chemists.

Any chemical analysis can be broken down into a number of stages that

include a consideration of the purpose of the analysis, the quality of the

results required and the individual steps in the overall analytical

procedure.

Related topics Analytical chemistry, its functions Automated procedures (H2)

and applications (A1) Computer control and data

Sampling and sample handling collection (H3)

H4 Data enhancement and databases

Chemical sensors and biosensors (H4)

(H1)

Analytical problems

Analytical

procedures